Manufacturing method for semiconductor integrated circuit device

ABSTRACT

A method for manufacturing a semiconductor integrated circuit device includes the step of forming an SOI device region and a bulk device region on an SOI type semiconductor wafer. The method includes: removing a BOX layer and an SOI layer in a bulk device region; and thereafter forming an STI region in both the SOI device region and the bulk device region. In the method, the STI region in the SOI device region is formed to extend through the BOX layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

The Present application claims priority from Japanese application JP2012-045346 filed on Mar. 1, 2012, the content of which is herebyincorporated by reference into this application.

BACKGROUND

The present invention relates to a method for manufacturing asemiconductor integrated circuit device (or semiconductor device), andin particular, a technique useful in applications to semiconductordevices having an SOI structure.

JP-A-10-303385 (Patent Document 1), has disclosed a technique forexposing a silicon substrate in a region constituting a part of the SOIsubstrate, namely a bulk device region, forming a memory cell region ofDRAM (Dynamic Random Access Memory) in the bulk device region, andforming a logic region in a region where the silicon substrate is notexposed, namely SOI device region.

JP-A-2007-184549 (Patent Document 2) has disclosed a technique forburying a device isolation insulative film in parallel with burying aninsulative film in a cavity portion to make an underlying oxide film inthe case of forming, from a single-crystal silicon substrate or thelike, a device having a bulk device region and a device region.

JP-A-2004-47844 (Patent Document 3) has disclosed a technique forexposing a silicon substrate in a bulk device region of a SOI substrate,causing an epitaxial silicon layer to grow in the region, and thenforming an STI (Shallow Trench Isolation) region.

WO2001/067509 (Patent Document 4) and U.S. Pat. No. 7,005,755 (PatentDocument 5) corresponding thereto have disclosed a technique for formingan alignment mark for superposition of a pattern in a part of an SOIsubstrate where an SOI layer and a BOX layer are removed.

JP-A-07-211610 (Patent Document 6) has disclosed a technique in formingan alignment mark for superposition of a pattern in an SOI substrate, bywhich an alignment mark is formed by removing an SOI layer and a BOXlayer, and etching an underlying substrate.

SUMMARY

With regard to a hybrid type SOI semiconductor integrated circuit devicehaving an SOI device region and a bulk device region on an SOIsubstrate, an SOI layer and a BOX layer are removed in a region to formthe bulk device region after the formation of an STI (Shallow TrenchIsolation) insulative film, in general. However, such process has aproblem that a step, i.e. the difference in height between the upperface of the STI insulative film and the upper face of the semiconductorsubstrate, becomes significant in the bulk device region.

The means for solving a problem like this will be described below.However, other problems and novel features thereof will become clearfrom the description hereof and the accompanying drawings.

Of the embodiments herein disclosed, a representative embodiment will bebriefly outlined below.

A method for manufacturing a semiconductor integrated circuit deviceaccording to the representative embodiment of the invention includesforming an SOI device region and a bulk device region on an SOI typesemiconductor wafer. In the method, a BOX layer and an SOI layer areremoved in the bulk device region before forming an STI region in thedevice regions. In the method, the STI region is formed to extendthrough the BOX layer in the SOI device region.

The effect achieved by the representative embodiment herein disclosed isas follows.

In the method for manufacturing a semiconductor integrated circuitdevice which includes forming an SOI device region and a bulk deviceregion on an SOT type semiconductor wafer, a BOX layer and an SOI layerare removed in the bulk device region before forming an STI region inthe device regions. The STI region is formed to extend through the BOXlayer in the SOI device region. Therefore, it becomes possible toprovide a device isolation structure with smaller steps, which issuitable for fine devices.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view for explaining an important part of the waferprocess in a method for manufacturing a semiconductor integrated circuitdevice (in the BOX & SOI layers-removing preceding process) according toone embodiment hereof, showing wafer-inward and -peripheral regions (thestep of SOI wafer introduction);

FIG. 2 is a sectional view for explaining an important part of the waferprocess in the method for manufacturing a semiconductor integratedcircuit device according to the embodiment (BOX & SOI layers-removingpreceding process), showing wafer-inward and -peripheral regions (thestep of removing BOX & SOI layers of a bulk device region and the like);

FIG. 3 is a sectional view for explaining an important part of the waferprocess in the method for manufacturing a semiconductor integratedcircuit device according to the embodiment (BOX & SOI layers-removingpreceding process), showing wafer-inward and -peripheral regions (Stepfor forming a resist pattern for trench formation);

FIG. 4 is a sectional view for explaining an important part of the waferprocess in the method for manufacturing a semiconductor integratedcircuit device according to the embodiment (BOX & SOI layers-removingpreceding process), showing wafer-inward and -peripheral regions (Stepfor burying an STI insulative film);

FIG. 5 is a sectional view for explaining an important part of the waferprocess in the method for manufacturing a semiconductor integratedcircuit device according to the embodiment (BOX & SOI layers-removingpreceding process), showing wafer-inward and -peripheral regions (Stepfor STI-CMP and removal of a silicon nitride film and others);

FIG. 6 is a sectional view for explaining an important part of the waferprocess in the method for manufacturing a semiconductor integratedcircuit device according to the embodiment (BOX & SOI layers-removingpreceding process), showing wafer-inward and -peripheral regions (gateelectrode-processing step);

FIG. 7 is a sectional view of the wafer-inward region (at the time ofthe completion of a gate electrode) for explaining an important part ofthe wafer process in the method for manufacturing a semiconductorintegrated circuit device according to the embodiment (BOX & SOIlayers-removing preceding process), which is taken along a differentdirection (i.e. the channel length direction) from the direction (i.e.the channel width direction) that FIG. 6 and other drawings are takenalong;

FIG. 8 is a view showing the layout of various regions on the front faceof the semiconductor wafer shown in FIGS. 1 to 7;

FIG. 9 is a view showing the layout of the chip region and itssurrounding regions of FIG. 8;

FIG. 10 is an enlarged top view of an alignment pattern surroundingcut-out region R1 of FIG. 9;

FIG. 11 is a sectional view of the wafer taken along the line A-A′ ofFIG. 10;

FIG. 12 is a top view of the whole wafer for explaining the detail ofthe wafer peripheral processing (the primary aligner outside peripheryexposing method) in the method for manufacturing a semiconductorintegrated circuit device according to the embodiment;

FIG. 13 is a top view showing the wafer and its surrounding portions forexplaining a modification (the primary aligner inside exposing method inwhich a mask is used) of the peripheral processing in the method formanufacturing a semiconductor integrated circuit device according to theembodiment;

FIG. 14 is a sectional view of the wafer-inward region for explaining animportant part (the step of SOI wafer introduction) of a wafer processin a method for manufacturing a semiconductor integrated circuit device(STI preceding process) according to another embodiment hereof;

FIG. 15 is a sectional view of the wafer-inward region for explaining animportant part (the step of forming a resist pattern for trenchformation) of the wafer process in the method for manufacturing asemiconductor integrated circuit device (STI preceding process)according to the embodiment hereof;

FIG. 16 is a sectional view of the wafer-inward region for explaining animportant part (the step of trench formation) of the wafer process inthe method for manufacturing a semiconductor integrated circuit device(STI preceding process) according to the embodiment;

FIG. 17 is a sectional view of the wafer-inward region for explaining animportant part (the step of burying an STI insulative film) of the waferprocess in the method for manufacturing a semiconductor integratedcircuit device (STI preceding process) according to the embodiment;

FIG. 18 is a sectional view of the wafer-inward region for explaining animportant part (the step of forming a resist pattern for reverse oxidefilm etching) of the wafer process in the method for manufacturing asemiconductor integrated circuit device (STI preceding process)according to the embodiment;

FIG. 19 is a sectional view of the wafer-inward region for explaining animportant part of the wafer process (the step of reverse oxide filmetching) in the method for manufacturing a semiconductor integratedcircuit device (STI preceding process) according to the embodiment;

FIG. 20 is a sectional view of the wafer-inward region for explaining animportant part (step of CMP and removal of silicon nitride film, etc.)of the wafer process in the method for manufacturing a semiconductorintegrated circuit device (STI preceding process) according to theembodiment;

FIG. 21 is a sectional view of the wafer-inward region for explaining animportant part (the step of processing a resist film for removal of BOX& SOI layers) of the wafer process in the method for manufacturing asemiconductor integrated circuit device (STI preceding process)according to the embodiment;

FIG. 22 is a sectional view of the wafer-inward region for explaining animportant part (BOX & SOI layers-removing step) of the wafer process inthe method for manufacturing a semiconductor integrated circuit device(STI preceding process) according to the embodiment;

FIG. 23 is a wafer top view showing an example of a harmful effect on aboundary portion of the bulk device region and the STI region, and thelike in the case where the height Dtb of the bulk device region STI ishigh (at the time of the completion of a gate electrode-processingstep);

FIG. 24 is a sectional view showing a wafer-inward region in STI formingprocess in a simple STI preceding process which is a comparative example(trench-burying step);

FIG. 25 is a sectional view showing the wafer-inward region in the STIforming process in the simple STI preceding process which is acomparative example (BOX & SOI layers-removing step);

FIG. 26 is a wafer sectional view for explaining the outline of themethod for manufacturing a semiconductor integrated circuit deviceaccording to one embodiment hereof (BOX & SOI layers-removing precedingprocess); and

FIG. 27 is a top view of the whole wafer for explaining the detail ofthe wafer peripheral processing in a modification of the exposure methoddescribed with reference to FIG. 12.

DETAILED DESCRIPTION Summary of the Embodiments

The summary of the representative embodiment herein disclosed will bedescribed first.

1. The method for manufacturing a semiconductor integrated circuitdevice includes the steps of:

(a) removing an SOI layer and a BOX layer in a part to make a bulkdevice region in each chip region on a first principal face side of anSOI type semiconductor wafer;

(b) after the step (a), forming a first STI region to extend through theBOX layer in a part to make an SOI device region in each chip region onthe first principal face side of the SOI type semiconductor wafer, andforming a second STI region in the bulk device region in each chipregion on the first principal face side of the SOI type semiconductorwafer; and

(c) after the step (b), forming MISFETs in the SOI device region and thebulk device region respectively.

2. In regard to the method for manufacturing a semiconductor integratedcircuit device as described in the above item No. 1, a lower end portionof the second STI region is lower than that of the first STI region.

3. In regard to the method for manufacturing a semiconductor integratedcircuit device as described in the above item No. 1 or 2, the step (c)includes the subsequent step of: (c1) patterning a gate electrode of theMISFET.

4. In regard to the method for manufacturing a semiconductor integratedcircuit device as described in any one of the above item Nos. 1 to 3,the step of forming an epitaxial semiconductor layer at least on thebulk device region is not included after the step (a) and before thestep (b).

5. in regard to the method for manufacturing a semiconductor integratedcircuit device as described in any one of the above items Nos. 1 to 4,the step (b) further includes: forming an alignment mark to use in thestep (c) in a dicing region on the first principal face side of the SOItype semiconductor wafer, the region having the SOI and BOX layersremoved therefrom.

6. In regard to the method for manufacturing a semiconductor integratedcircuit device as described in the above item No. 5, the alignment markis mainly composed of an STI insulative film formed concurrently withformation of the first and second STI regions.

7. In regard to the method for manufacturing a semiconductor integratedcircuit device as described in any one of the above items Nos. 1 to 6,the step (a) further includes: removing the SOI and BOX layers in awafer-peripheral region on the first principal face side of the SOI typesemiconductor wafer.

8. In regard to the method for manufacturing a semiconductor integratedcircuit device as described in the above item No. 7, a part to removethe SOI and BOX layers from the wafer-peripheral region is defined byperipheral exposure.

9. In regard to the method for manufacturing a semiconductor integratedcircuit device as described in the above item No. 7, a part to removethe SOI and BOX layers from the wafer-peripheral region is defined byexposure using a mask pattern.

10. In regard to the method for manufacturing a semiconductor integratedcircuit device as described in the above item No. 8, the peripheralexposure is executed before a primary exposure for defining the bulkdevice region in each chip region.

11. The method for manufacturing a semiconductor integrated circuitdevice includes the steps of:

(a) removing an SOI layer and a BOX layer in a part to make a bulkdevice region in each chip region on a first principal face side of anSOI type semiconductor wafer;

(b) after the step (a), forming a first STI region in a part to make anSOI device region in each chip region on the first principal face sideof the of the SOI type semiconductor wafer, and forming a second STIregion in the bulk device region in each chip region on the firstprincipal face side of the SOI type semiconductor wafer; and

(c) after the step (b), forming MISFETs in the SOI device region and thebulk device region respectively.

In the method, the step of forming an epitaxial semiconductor layer atleast on the bulk device region is not included after the step (a) andbefore the step (b).

12. In regard to the method for manufacturing a semiconductor integratedcircuit device as described in the above item No. 11, a lower endportion of the second STI region is lower than that of the first STIregion.

13. In regard to the method for manufacturing a semiconductor integratedcircuit device as described in the above item No. 11 or 12, the step (c)includes the subsequent step of: (c1) patterning a gate electrode of theMISFET.

14. In regard to the method for manufacturing a semiconductor integratedcircuit device as described in any one of the above items Nos. 11 to 13,the step (b) further includes: forming an alignment mark to use in thestep (c) in a dicing region on the first principal face side of the SOItype semiconductor wafer, the region having the SOI and BOX layersremoved therefrom.

15. In regard to the method for manufacturing a semiconductor integratedcircuit device as described in the above item No. 14, the alignment markis mainly composed of an STI insulative film formed concurrently withformation of the first and second STI regions.

16. In regard to the method for manufacturing a semiconductor integratedcircuit device as described in any one of the above items Nos. 11 to 15,the step (a) further includes: removing the SOT and BOX layers in awafer-peripheral region on the first principal face side of the SOI typesemiconductor wafer.

17. in regard to the method for manufacturing a semiconductor integratedcircuit device as described in the above item No. 16, a part to removethe SOT and BOX layers from the wafer-peripheral region is defined byperipheral exposure.

18. in regard to the method for manufacturing a semiconductor integratedcircuit device as described in the above item No. 16, a part to removethe SOI and BOX layers from the wafer-peripheral region is defined byexposure using a mask pattern.

19. In regard to the method for manufacturing a semiconductor integratedcircuit device as described in the above item No. 17, the peripheralexposure is executed before a primary exposure for defining the bulkdevice region in each chip region.

[The Description Format Hereof, and Explanation of Basic Terms, and UseThereof]

1. The description of the embodiment herein is divided into two or moresections on an as-needed basis for convenience in some cases. However,the sections are not independent of each other, and they cover a part ofone embodiment, a detailed part of the other part, or apart or all of amodification thereof, unless clearly stated as not being so inparticular. The iteration of the description concerning like parts isavoided in principle. Further, each constituent of one embodiment is notessential unless clearly stated as not being so in particular, limitedto that number theoretically, or clearly judged as not being so from thecontext.

Further, the word “semiconductor device” or “semiconductor integratedcircuit device” used herein primarily refers to a device in which asemiconductor chip or the like, e.g. a single-crystal silicon substratehas various kinds of discrete transistors (active elements), andresistors, capacitors and other elements arranged around the transistorsintegrated thereon, or a device into which such semiconductor chip ispackaged. The representative examples of the various transistors includeMISFET (Metal Insulator Semiconductor Field Effect Transistor) typifiedby MOSFET (Metal Oxide Semiconductor Field Effect Transistor). Therepresentative examples of the integrated circuit structures include aCMIS (Complementary Metal Insulator Semiconductor) type integratedcircuit typified by a CMOS (Complementary Metal Oxide Semiconductor)type integrated circuit having a combination of an N-channel type MISFETand a P-channel type MISFET.

The wafer process of today's semiconductor integrated circuit device,namely LSI (Large Scale Integration) is usually considered being dividedinto two phases. Specifically, the first one is FEOL (Front End of Line)phase. The FEOL phase is composed of steps, i.e. from the step ofloading a silicon wafer as a primary material roughly to a group ofpremetal steps (including the step of forming an interlayer insulativefilm, etc. between the lower end of a M1 wiring layer and a gateelectrode structure, the step of forming a contact hole, and the step ofburying a tungsten plug). The second one is BEOL (Back End of Line)phase. The BEOL phase is composed of steps, i.e. from the step offorming the M1 wiring layer roughly to the step of forming a pad openingin a final passivation film on an aluminum-based pad electrode (if awafer-level packaging is present, including the step of packaging).

2. Likewise, in the descriptions of the embodiment and others, theexpression “X including A” concerning a material, a composition or thelike is not intended to exclude that X includes an element other than Aas one of main constituents, unless clearly stated as not being so inparticular, or clearly judged as not being so from the context. In termsof the constituents, for example, it means “X including A as a mainconstituent”. Further, e.g. “silicon member” is not limited to puresilicon. It is obvious that it includes members including a SiGe alloy,other multi-element alloys having silicon as main constituents, otheradditives, etc.

Likewise, “silicon oxide film” and “silicon oxide-based insulative film”each include not only relatively pure undoped silicon dioxide, but alsoother insulative films having other silicon oxides as a mainconstituent. Impurity-doped silicon oxide-based insulative films of e.g.TEOS-based silicon oxide, PSG (Phosphorus Silicate Glass), and BPSG(Borophosphosilicate Glass) are also silicon oxide films.

Also, coating films of an SOG (Spin On Glass), an NSC (Nano-ClusteringSilica), and the like as well as a thermal oxide film and a CVD oxidefilm are a silicon oxide film or a silicon oxide-based insulative film.In addition, Low-k insulative films of an FSG (Fluorosilicate Glass), aSiOC (Silicon Oxicarbide) or a carbon-doped silicon oxide (Carbon-dopedSilicon oxide), an OSG (Organosilicate Glass), and the like are also asilicon oxide films or a silicon oxide-based insulative film. Further, asilica-based Low-k insulative film (porous insulative film) formed by alike member having pores introduced thereinto is also a silicon oxidefilm or a silicon oxide-based insulative film.

As a silicon-based insulative film commonly used in a semiconductorfield as well as a silicon oxide-based insulative film, a siliconnitride-based insulative film is included. The materials for such kindof films include SiN, SiCN, SiNH and SiCNH. Now, “silicon nitride”described herein includes both of SiN and SiNH unless clearly stated asnot being so in particular. Likewise, “SiCN” includes both of SiCN andSiCNH unless clearly stated as not being so in particular.

Incidentally, SiC has properties similar to those of SiN. It is oftenthe case that SiON should be rather classified as a silicon oxide-basedinsulative film.

A silicon nitride film is often used as an etching-stop film, namely aCESL (Contact Etch-Stop Layer) in SAC (Self-Aligned Contact) technology,and in addition it is also used as a stress-applying film in SMT (StressMemorization Technique).

Likewise, “nickel silicide” usually refers to nickel monosilicide.However, it includes not only relatively pure nickel monosilicide, butalso an alloy, a mixed crystal and other materials, which contain nickelmonosilicide as a main constituent. The silicide may be not only nickelsilicide, but also cobalt silicide, titaniumsilicide, tungsten silicideand the other materials, which have a track record in conventional use.In addition to a Ni (nickel) film, a nickel alloy film, e.g. a Ni—Ptalloy film (alloy film of Ni and Pt), a Ni—V alloy film (alloy film ofNi and V), a Ni—Pd alloy film (alloy film of Ni and Pd), a Ni—Yb alloyfilm (alloy film of Ni and Yb), or a Ni—Er alloy film (alloy film of Niand Er) may be used as a metal film for silicification. The silicideshaving nickel as a primary metal element are referred to as“nickel-based silicide”.

3. Likewise, the preferred embodiments will be shown in terms offigures, position and attributes. However, it is obvious that theinvention is not strictly limited to the embodiments unless clearlystated as not being so in particular, or clearly judged as not being sofrom the context.

4. When citing a certain numerical value, or a certain numericalquantity, the certain numerical value or quantity may be a value aboveor below the certain value or quantity unless clearly stated as notbeing so in particular, limited to that number theoretically, or clearlyjudged as not being so from the context.

5. When using the word “wafer”, the word refers to typically amonocrystalline silicon wafer which has a semiconductor integratedcircuit device (or a semiconductor device, or an electronic device)formed thereon. However, it is obvious that what is referred to by theword includes an epitaxial wafer, and a complex wafer having aninsulative substrate such as an SOT substrate or an LCD glass substrate,and a semiconductor layer or the like.

6. The various kinds of regions are handled herein, which include aregion lying on a wafer or a surrounding region thereof (e.g. a chipregion). However, some of these regions cannot be directly recognized asan externally appearing geometry depending on the step. However, suchregions refer to a specific region located on a wafer in a positionmeasured from a predetermined reference point, and forming an entity.

In addition, the various regions often used herein will be describedbriefly. “SOI device region” refers to a region where an SOI typetransistor (i.e. a transistor formed on an SOI structure) is formed, and“bulk device region” refers to a region where a bulk type transistor(i.e. a transistor formed on a bulk region on a substrate) is formed.

Further, “STI region” refers to a region where an STI type deviceisolation insulative film, i.e. an STI insulative film is formed. Now,it is noted that “reverse oxide film etching” in connection with the STIprocess refers to a pre-CMP etching which is performed by use of areverse etching mask (corresponding to a reverse pattern of a resistpattern for trench formation) having an opening a little smaller thanthe width of a targeted part so as to prevent a buried oxide film of thepart corresponding to a relatively wide active region from excessivelyremaining. Then, the ratio of an opening size of the reverse etchingmask (resist film) to the size of an actual targeted active region issometimes referred to as “reverse-opening-size-reduction rate”. However,while the word “reduction rate” is used, the reduction is not made at afixed rate typically. A result from the subtraction of a fixed lengthsuch as an alignment margin from the size of an original active regionis made the opening size (e.g. in the case of a uniform reduction methodas described below). Therefore, as to a part corresponding to an activeregion which is equal to or less than two or three times the alignmentmargin in size, the opening size is zero. The description on theembodiments below covers the embodiment in which substantially the samereverse-opening-size-reduction rate is used for an SOI device region anda bulk device region, and the embodiment in which a smallerreverse-opening-size-reduction rate is used for a bulk device region(i.e. the opening size is made larger and possibly, a negative reductionrate may be used). In such cases, the method applied in the formerembodiment is referred to as “uniform reduction method”, and the methodin the latter embodiment is referred to as“bulk-device-side-etching-amount-increasing method”.

It is needless to say that the reverse oxide film etching is notessential unless clearly stated as being essential in particular.

Further, “wafer-peripheral region” refers to an annular regionsurrounding a wafer and ranging to a few millimeters radially, which iscomplementary to “wafer-inward region” in concept. In addition, italmost coincides with “peripheral exposure region” or “edge-rinseregion” in the resist processing.

Likewise, “chip region” and “dicing region (scribing region)” arecomplementary to each other in concept. The “alignment mark formationregion” is usually located in the dicing region. Now, it is needless tosay that the “dicing region” is not limited to a region to be dividedinto chips by dicing.

In the embodiment described below, chiefly a “unit shot region” includesone chip region. However, it may include a plurality of chip regions.The “actual unit shot region” principally refers to a unit shot regioncorresponding to a chip region, which forms a product. The “dummy unitshot region” principally refers to a unit shot region located in thevicinity of the wafer-peripheral region where the “unit shot region”lies out of the “wafer-inward region”, which is to be subjected to thewafer peripheral exposure.

7. The “SOI type semiconductor wafer” herein refers to a wafer having anSOI structure on the almost entire surface of the wafer or a partthereof on the side of its front face. Here, the SOI structure generallyrefers to a structure such that a semiconductor thin film such as an SOIlayer is formed on a thin insulative film such as a BOX layer on thefront face side of a semiconductor substrate such as a siliconsubstrate. It is not intended that “BOX layer” is herein limited to aparticular manufacturing method, which refers to an underlyinginsulative film of SOI layer in a wide sense. Further, it is notintended that “SOI layer” is limited to a silicon or silicon-basedmember. Except silicon and SiGe, it may be e.g. a germanium-basedsemiconductor member, or III-V group semiconductor member.

8. The word “peripheral exposure” herein refers to a main exposure,namely the exposure of a wafer-peripheral region, as one of waferperipheral exposures, which is performed outside an aligner forperforming the exposure of a wafer-inward region. The photolithographicprocessing system forms a Litho-Cluster which typically has alithographic processing track including an aligner part such as ascanner, and a coater. In general, a peripheral exposure unit forperforming the peripheral exposure is provided in the lithographicprocessing track.

Further Detailed Description of the Embodiments

The embodiments of the invention will be described further in detail.The same or like parts in the drawings are identified by the same orsimilar symbol or reference numeral, and the iteration of thedescription thereof is avoided in principle.

In the accompanying drawings, if hatching makes the representation morecomplicated or if it is possible to clearly distinguish a part or memberfrom a gap, the hatching or the like is possibly omitted even with across section. Likewise, with respect to even a closed hole in planeview, if it is clearly identified from the description or the like, thedrawing of its background border line is possibly omitted. Further, evenif a part or member of interest is not presented in sectional view, thehatching is possibly made for clearly showing that it is not a gap.

In the case of referring to the parts or members to be alternativelytermed with the one accompanied with “first” and the other with“second”, such parts or members are associated with the termsaccompanied with the words “first” and “second” according to therepresentative embodiment, and exemplified in some cases. However, it isobvious that what is referred to by e.g. a term accompanied by the word“first” is not limited to the exemplified option.

The prior patent applications which have disclosed the SOI processinclude e.g. Japanese Patent Application number 2011-223666, filed onOct. 11, 2011 in Japan.

1. Description of Important Parts of the Wafer Process in the Method forManufacturing a Semiconductor Integrated Circuit Device According to OneEmbodiment Hereof (BOX & SOI Layers-Removing Preceding Process) andOthers (See FIGS. 1 to 7, Chiefly).

This section describes an embodiment of the wafer process between theloading of a wafer and the provisional completion of a gate structure.While in the description below, an SOC chip is taken as an example ofthe device in connection with the present invention, and is explainedconcretely, it is needless to say that the envisioned device may be achip for exclusive memory use. With the embodiment below, the concretedescription is presented taking a product of 28-nm-technology nodegeneration as an example chiefly. However, it is obvious that thedescription below is applicable to other generations.

Now, it is noted that the reverse oxide film etching in the STI processis to be described in the fifth section in detail with reference toFIGS. 18 and 19, and therefore the description thereof will be omittedhere in principle.

It is needless to say that the wafer peripheral processing (i.e. removalof a BOX layer, an SOI layer and the like in the wafer peripheralportion) as a countermeasure against exfoliation, which will bedescribed in this section, is not essential. However, the troublesincluding exfoliation in a wafer peripheral portion can be reduced byperforming the processing.

Further, in the embodiment below, a typical FD-SOI (Fully DepletedSilicon on Insulator) device will be taken as an example, and describedspecifically. However, it is obvious that the device may be a so-calleddopantless channel type FD-SOI device.

It is noted that while the integrated circuit described here takes aCMOS circuit structure chiefly in the SOI device region 3 and the bulkdevice region 4, only a portion of an N-channel type device is shown toavoid complexity in the drawing in principle.

FIG. 1 is a sectional view for explaining an important part of the waferprocess in a method for manufacturing a semiconductor integrated circuitdevice according to one embodiment hereof (BOX & SOI layers-removingpreceding process), showing wafer-inward and -peripheral regions (thestep of SOI wafer introduction). FIG. 2 is a sectional view forexplaining an important part of the wafer process in the method formanufacturing a semiconductor integrated circuit device according to oneembodiment hereof (BOX & SOI layers-removing preceding process), showingwafer-inward and -peripheral regions (Step for removing BOX & SOI layersof a bulk device region and the like). FIG. 3 is a sectional view forexplaining an important part of the wafer process in the method formanufacturing a semiconductor integrated circuit device according to oneembodiment hereof (BOX & SOI layers-removing preceding process), showingwafer-inward and -peripheral regions (the step of processing a resistfilm for trench formation), FIG. 4 is a sectional view for explaining animportant part of the wafer process in the method for manufacturing asemiconductor integrated circuit device according to one embodimenthereof (BOX & SOI layers-removing preceding process), showingwafer-inward and -peripheral regions (Step for burying an STI insulativefilm). FIG. 5 is a sectional view for explaining an important part ofthe wafer process in the method for manufacturing a semiconductorintegrated circuit device according to one embodiment hereof (BOX & SOIlayers-removing preceding process), showing wafer-inward and -peripheralregions (the step of STI-CMP and removal of a silicon nitride film andothers), FIG. 6 is a sectional view for explaining an important part ofthe wafer process in the method for manufacturing a semiconductorintegrated circuit device according to one embodiment hereof (BOX & SOIlayers-removing preceding process), showing wafer-inward and -peripheralregions (the step of gate electrode processing). FIG. 7 is a sectionalview of the wafer-inward region (at the time of the completion of a gateelectrode) for explaining an important part of the wafer process in themethod for manufacturing a semiconductor integrated circuit deviceaccording to one embodiment hereof (BOX & SOI layers-removing precedingprocess), which is taken along a different direction (i.e. the channellength direction) from the direction (i.e. the channel width direction)that FIG. 6 and other drawings are taken along. With reference to thedrawings, an important part of the wafer process and other things in themethod for manufacturing a semiconductor integrated circuit deviceaccording to one embodiment hereof (BOX & SOI layers-removing precedingprocess) will be described.

First, a P-type SOI semiconductor wafer 1 is prepared, which has a BOXoxide film 14 (BOX layer) having a thickness of about 10 nm (preferablyfrom approximately several to 20 nm), and an SOI layer 15 having athickness of about 26 nm (preferably from approximately several to 30nm), as shown in FIG. 1. Specifically, a P-type monocrystalline siliconwafer (with a P-type substrate part 1 s) is prepared, which has an SOIlayer 15 and a BOX oxide film 14 formed almost all over the surface onthe side of the device-mount face 1 a (i.e. a principal face opposite tothe backside 1 b). It is assumed here that the wafer 1 has a diameter ofe.g. 300^(φ), however it may be 450^(φ), 200^(φ), or another size ifrequired. It is preferable that the P-type substrate part 1 s and theSOI layer 15 have an electrical resistivity of e.g. 1 to 10 Ωcmapproximately. The orientation of the wafer 1 can be made e.g. (100),however another orientation may be arranged. Incidentally, in FIG. 1,the right-side region partitioned off by a broken line is thewafer-peripheral region 6, and the left-side region is the wafer-inwardregion 7.

Next, as shown in FIG. 2, a resist film 16 for bulk device regiondefinition is formed almost all over the surface of the wafer 1 on theside of the face 1 a thereof. The resist film 16 for bulk device regiondefinition is patterned by e.g. a typical photolithography.Subsequently, the patterned resist film 16 for bulk device regiondefinition is used as a mask to remove the SOI layer 15 in the bulkdevice region 4 and in the wafer-peripheral region 6 by e.g. dryetching, in which e.g. a halogen-based etching gas is used. Then, theBOX layer 14 is removed in the bulk device region 4 and in thewafer-peripheral region 6 by e.g. wet etching, in which e.g. ahydrofluoric acid-based etchant is used. After that, the disused resistfilm 16 for bulk device region definition is removed by e.g. ashing. Theexposure of the resist film 16 for bulk device region definition in thewafer-peripheral region 6 will be described in detail in the sections 3and 4, and therefore, the description thereof is omitted here. Byremoving the BOX layer 14 and SOI layer 15 in the peripheral portions ofthe wafer in this way, the generation of dust in the subsequent stepscan be reduced.

Then, a pad silicon oxide film 21 having a thickness of about 10 nm isformed almost all over the surface of the wafer 1 on the side of theface 1 a by e.g. CVD (Chemical Vapor Deposition), as shown in FIG. 3.Subsequently, a silicon nitride film 22 for a stopper of CMP (ChemicalMechanical Polishing) is formed by e.g. CVD almost all over the surfaceof the wafer 1 on the side of the front face 1 a to have a thickness ofe.g. about 60 nm. Then, a resist film 18 for trench formation is formedalmost all over the surface of the wafer 1 on the side of the front face1 a; the resist film 18 for trench formation is patterned by e.g. atypical photolithography.

Subsequently, as shown in FIG. 4, a trench which will form an STI regionis formed by e.g. anisotropic dry etching while using, as a mask, thepatterned resist film 18 for trench formation. In this embodiment, thetrench extends through the BOX layer 14 and reaches the inside of thesubstrate 1 s in the SOI device region 3. By making the arrangement likethis, the harmonization with the depth of the trench in the bulk deviceregion 4 can be ensured. Also, the mutual isolation between back-gateregions in the SOI device region 3 can be enhanced.

Subsequently, a liner silicon oxide film is formed on a semiconductorsurface exposed on the side of the front face 1 a of the wafer 1 by e.g.thermal oxidation (which is not shown to avoid increasing the complexityof the drawing).

Subsequently, a silicon oxide film is formed as an STI insulative film17 almost all over the surface of the wafer 1 on the side of the frontface 1 a by e.g. HDP (High Density Plasma)-CVD (the silicon oxide filmmay be formed according to another method).

Subsequently, the reverse oxide film etching is performed with theresist film for reverse oxide film etching as a preparation for CMP, asdescribed in the fourth section. However, in this embodiment, theprocessing is performed according to the uniform reduction method unlikethe case of the fourth section. While the method to apply to thisprocessing may be the bulk-device-side-etching-amount-increasing methodas in the case of the fourth section, the uniform reduction method hasthe advantage that the process is simpler. The application of thebulk-device-side-etching-amount-increasing method brings about the sameadvantage as the method applied in the case of the fourth section does.

Next, CMP is executed on the side of the front face 1 a of the wafer 1,whereby the front face of the wafer is planarized. Then, silicon nitridefilm 22 is removed by e.g. wet etching, in which the etchant usedtherefor is e.g. a hot phosphoric acid. Subsequently, the pad siliconoxide film 21 is removed by e.g. wet etching, in which the etchant ise.g. a hydrofluoric acid-based etchant. As a result, the structure asshown in FIG. 5 is obtained. The STI insulative film 17 is buried ineach trench as shown in FIG. 5; the STI regions 17, 17 s and 7 b, i.e.the first and second STI regions 17 s and 17 b are formed. In this case,as clear from FIG. 5, an STI height Htb (i.e. bulk device region STIheight) in the bulk device region 4 is relatively low with respect tothe front face of the semiconductor substrate 1 s. This is useful toavoid that a step deteriorates the effect of the photolithography. Thereis an SOI-bulk inter-region SOI bottom step Dsb between the STI region17 b (second STI region) of the bulk device region, and the STI region17 s (first STI region) of the SOI device region. Therefore, the STIregion 17 b (i.e. second STI region) of the bulk device region is deeperin terms of the depth of the STI region (i.e. the height of the bottomface of the STI region) with respect to the surface of the semiconductorsubstrate 1 s. This is advantageous to a bulk device which has a highoperation voltage in general.

The steps can be simplified by arranging a process not to involve thestep of forming an epitaxial semiconductor layer at least on the bulkdevice region 4 after the removal of the BOX layer 14 and the SOI layer15 and before the formation of the STI region 17 as in this embodiment,which is optional.

Subsequently, as shown in FIG. 6, a SiON film serving as e.g. a gateinsulating film 24 and having an EOT (Equivalent Oxide Thickness) ofabout 1.9 nm is formed almost all over the surface of the wafer 1 on theside of the front face 1 a.

Subsequently, a TiN film (having a thickness of e.g. 20 nmapproximately) is formed almost all over the surface of the wafer 1 onthe side of the front face 1 a by sputtering, as a part of the gateelectrode 25. Then, a polycrystalline silicon film (having a thicknessof e.g. 80 nm approximately) is formed almost all over the surface ofthe wafer 1 on the side of the front face 1 a by e.g. CVD, as a part ofthe gate electrode 25. It is noted that an amorphous silicon film may beformed instead of the polycrystalline silicon film. Next, a siliconnitride film (having a thickness of e.g. 50 nm approximately) is formedalmost all over the surface of the wafer 1 on the side of the front face1 a by e.g. CVD, as a cap insulative film 30.

After that, the cap insulative film 30, the gate electrode 25 and thegate insulating film 24 (gate stack structure) are patterned by thetypical photolithography.

Subsequently, N-type source and drain regions 28 s of MISFET of the SOIdevice region, and N-type source and drain regions 28 b of MISFET of thebulk device region, which are required, are formed by e.g. ionimplantation while using a gate stack structure and side walls 27, asshown in FIG. 7. Incidentally, FIG. 7 presents a cross section of thewafer perpendicular to a cross section drawn in FIG. 6 so that a source,a drain and other parts can be seen. Basically, an N-type MISFET (Qs)which is a MISFET of the SOI device region, and an N-type MISFET (Qb)which is a MISFET of the bulk device region have been formed by theabove steps. Now, it is noted that the SOI device region (e.g. a channelpart) takes a P-type doped structure in this embodiment, however it maybe arranged to have a non-doped structure.

After that, the wafer goes through e.g. the formation of a premetalinsulative film and a contact hole, the burying of a tungsten plug, andBEOL phase including the step of making interconnections (which may becomposed of e.g. multilayered copper-based buried lines, aluminum-basedlines, or a wiring system with both types of lines used therein), and isdivided into chips by dicing or the like. The chips are arranged intopackages on an as-needed basis. Then, finished devices are obtained.

The BOX & SOI layers-removing preceding process has the advantage thatin the case of using the reverse oxide film etching of the uniformreduction method (with a positive reduction rate), a sufficientalignment margin can be set for an active end portion in reverse oxidefilm etching.

2. Descriptions of the Layout of a Wafer and Parts Including a ChipRegion, in the Method for Manufacturing a Semiconductor IntegratedCircuit Device According to the Embodiment Hereof, and the AlignmentMark, etc. to be Formed in STI Step (with Reference to FIGS. 8 to 11,Chiefly)

An example of the layout of various parts on the wafer, the alignmentmark, and others will be described here in connection with the waferprocess described in the section 1. It goes without saying that variousstructures (the notch, and the alignment mark) described here are notessential, and various changes and modifications may be made as in thecase of the above-described process.

FIG. 8 is a view showing the layout of various regions on the front faceof the semiconductor wafer shown in FIGS. 1 to 7. FIG. 9 is a viewshowing the layout of the chip region of FIG. 8 and the regions aroundit. FIG. 10 is an enlarged top view of an alignment pattern surroundingcut-out region R1 of FIG. 9. FIG. 11 is a wafer sectional view takenalong the line A-A′ of FIG. 10. The layout of a wafer and partsincluding a chip region, in the method for manufacturing a semiconductorintegrated circuit device according to the embodiment hereof, and thealignment mark, etc. to be formed in STI step will be described withreference to the drawings.

FIG. 8 shows an example of the layout of various regions in the frontface 1 a (first principal face) of the wafer 1 in the course of thewafer process of the semiconductor integrated circuit device (at thesame time as FIG. 5). As shown in FIG. 8, the wafer 1 has a notch 5(crystal orientation indicator part) or the like in general. The frontface 1 a thereof is divided into e.g. a wafer-peripheral region 6 and awafer-inward region 7. In the wafer-inward region 7, lots of chipregions 2 and 2 a are laid out substantially in a matrix-like form.Incidentally, the cross sections shown in FIGS. 1 to 6 substantiallycorrespond to the cross section taken along the line X-X′ of FIG. 8.

FIG. 9 presents the chip region 2 a and its surroundings of FIG. 8 in anenlarged form. As shown in FIG. 9, the chip regions 2 a, 2 b, 2 c, 2 d,2 e, 2 f, 2 g, 2 h, and 2 i are arranged in a lattice-like form tosandwich a scribing region 8 (dicing region) therebetween in thisembodiment, for example. In each chip region 2 a (, 2 b, 2 c, 2 d, 2 e,2 f, 2 g, 2 h, 2 i), the SOI device region 3 and the bulk device region4 are provided. The SOI device region 3 corresponds to a core logiccircuit part, or a memory mat part, for example, in terms of thecircuit. The bulk device region 4 corresponds to a core logic peripheralcircuit part, an I/O circuit part, a memory peripheral circuit part, orthe like.

An alignment mark formation region 11, and a test pattern region 12having a BOX layer and an SOI layer, where TEG (Test Element Group) orthe like is disposed, are provided in the dicing region 8 between thechip region 2 a and the chip region 2 e, for example. In thisembodiment, an exposure unit shot region 9 includes one chip region 2 a,and therefore it includes almost all the chip region 2 a and itssurrounding dicing region 8.

Next, an enlarged view of the alignment pattern surrounding cut-outregion R1 shown in FIG. 9 is presented in FIG. 10. As shown in FIG. 10,an alignment mark 10 composed of e.g. lots of rectangles is provided inthe alignment mark formation region 11. The alignment mark 10 is anexample of a mark formed in an STI region forming process, and is mainlymade of an STI insulative film 17. Specifically, the alignment mark 10is made of an insulative film formed concurrently with STI insulativefilm buried in a trench formed in the step of trench formation includedin the STI step. In addition, the BOX layer 14 and the SOI layer 15 areremoved in the alignment mark formation region 11 in parallel with thestep as shown with reference to FIG. 2. The reason for this is the BOXlayer 14 and the SOI layer 15 cause an interference fringe such as amoire fringe, which can interfere with the detection of a position. Inother words, the alignment mark formation region 11 makes a regionsimilar to the bulk device region. Therefore, other regions in thealignment mark formation region 11 as well as the alignment mark 10 makean active region or a semiconductor substrate-exposed region 29. Ifthere is not a region similar to the SOI device region in the vicinityof the alignment mark 10 like this, the increase in the accuracy ofpositioning is obtained.

On the other hand, the test pattern region 12 to hold the TEG or thelike usually has a part which makes a region similar to the SOI deviceregion; the similar region has the BOX layer 14 and the SOI layer 15.From the viewpoint of reducing dust and the like, it is not desired thatthe region similar to the SOI device region and the region similar tothe bulk device region are finely divided and laid out in the part ofthe dicing region 8 other than the test pattern region 12 and thealignment mark formation region 11. However, it is not essential.

FIG. 11 shows a cross section taken along the line A-A′ of FIG. 10. Asshown in FIG. 11, the alignment mark formation region 11 has the samecross section structure as that of the bulk device region 4 shown inFIG. 5 at the time when the wafer is in the situation shown in FIG. 5.

Next, these regions and others will be described in association with thewafer process (particularly the exposure process) described in thesection 1. Specifically, the alignment mark 10 as shown in FIG. 10 isformed in parallel with the steps as described with reference to FIGS. 3to 5. The alignment mark 10 is to be used for e.g. the alignment inprocessing the gate electrode as described with reference to FIG. 6.

3. Detailed Description of the Peripheral Processing (i.e. WaferPeripheral Exposure Processing) in the Method for Manufacturing aSemiconductor Integrated Circuit Device According to One EmbodimentHereof—Description of the Primary Aligner Outside Periphery ExposingMethod (with Reference to FIGS. 12 and 27, Mainly.)

One example of the specific method (particularly a photolithographytechnique associated with FIG. 2) for the removal of the BOX layer 14and the SOI layer 15 in the wafer-peripheral region 6, which has beendescribed in the section 1 (with reference to FIG. 2), will be describedin this section. It goes without saying that the method described hereis not essential, and various changes and modification thereof may bemade as in the case of the above-described process.

FIG. 12 is a top view of the whole wafer for explaining the detail ofthe peripheral processing (the primary aligner outside peripheryexposing method) in the method for manufacturing a semiconductorintegrated circuit device according to one embodiment hereof. FIG. 27 isa top view of the whole wafer for explaining the detail of the waferperipheral processing in a modification of the exposure method to bedescribed with reference to FIG. 12. The detail of the peripheralprocessing (the primary aligner outside periphery exposing method) inthe method for manufacturing a semiconductor integrated circuit deviceaccording to one embodiment hereof will be described with reference tothe drawings.

In FIG. 12, the regions on the wafer 1 shown in FIG. 8 are classifiedfor the sake of explanation of the exposure, provided that the point ofprocessing the wafer put in the condition shown in FIG. 12 is the sameas the time when the wafer is in the condition shown in FIG. 2. As shownin FIG. 12, unit shot regions 9 are set substantially in a matrix-likeform in the wafer-inward region 7 in the front face 1 a of the wafer 1.In this embodiment, the wafer-peripheral region 6 corresponds to aperipheral exposure region 20, namely a region to go through theperipheral exposure.

The photolithography of FIG. 2 is executed according to the followingprocedure which includes, in turn:

(1) the step of forming a resist film (e.g. application of a positiveresist film);

(2) the peripheral exposure step (wherein the peripheral exposure region20 is exposed to light while using a spot beam of ultraviolet lighthaving the same wavelength as that of light used for regular exposure);

(3) regular exposure step (wherein a scanner, a stepper, or the like isused to perform the exposure for defining the bulk device region 4, etc.described with reference to FIG. 2 while using ultraviolet light ofi-line having a wavelength of 365 nm);

(4) executing PEB (Post Exposure Bake); and

(5) executing the development, post bake, etc.

This method has the advantage that the aligner's throughput is neverreduced because no aligner is used. Incidentally, the wavelength used inthe regular exposure step may be another wavelength other than theaforementioned one. In addition, as long as the resist film is exposedto light, the wavelength of the peripheral exposure step is notnecessarily required to be the same as that of the regular exposurestep. Further, a chemically amplified resist may be used as the resistfilm. Incidentally, a chemically amplified resist is said to be suitablefor today's microfabrication in general. In addition, the resist film isnot necessarily of positive type. In the case of a negative type resistused for the resist film, no resist film is formed on a wafer peripheralportion even when the peripheral exposure is not performed.Incidentally, as shown in FIG. 27, in the case of using an aligner tocause the exposure of a unit shot on the wafer peripheral portion (e.g.for the purpose of ensuring the uniformity of a pattern for CMP), aresist film can be prevented from being formed on the wafer peripheralportion after development by rinsing an edge in the resist processing.Further, in the case of a positive resist, the peripheral exposure asdescribed above is applicable.

Further, the peripheral exposure step is executed before the regularexposure step in this embodiment. The reason for this is to minimize theprocessing time between the regular exposure and the PEB. However, thisis not essential, and therefore it is obvious that the order ofexecution of the steps can be counterchanged with each other.

The primary aligner outside periphery exposing method is advantageous inthat the throughput of the primary aligner (i.e. the primary aligner) isnot reduced.

4. Description of Modification of the Peripheral Processing in theMethod for Manufacturing a Semiconductor Integrated Circuit DeviceAccording to One Embodiment Hereof—Description of the Primary AlignerInside Exposing Method in which a Mask is Used (with Reference to FIG.13, Mainly)

In this section, a modification of the wafer peripheral exposureprocessing explained in the section 3 will be described.

FIG. 13 is a top view showing the wafer and its surrounding portions forexplaining a modification (the primary aligner inside exposing method inwhich a mask is used) of the peripheral processing in the method formanufacturing a semiconductor integrated circuit device according to oneembodiment hereof. With reference to the drawing, the modification ofthe peripheral processing in the method for manufacturing asemiconductor integrated circuit device according to one embodimenthereof, namely the primary aligner inside exposing method in which amask is used will be described.

FIG. 13 to which reference is made in this embodiment corresponds toFIG. 12. As shown in FIG. 13, the wafer peripheral exposure processingis executed in the regular exposure step (in the primary aligner) inthis embodiment. Therefore, the flow of the processing is as follows, inturn:

(1) the step of forming a resist film (e.g. application of a positiveresist film);

(2) wafer peripheral exposure & regular exposure step (wherein ascanner, stepper, or the like is used to perform the exposure fordefining the bulk device region 4, etc. described with reference to FIG.2 and to perform the wafer peripheral exposure processing while usinge.g. ultraviolet light of i-line having a wavelength of 365 nm);

(3) Executing PEB (Post Exposure Bake); and

(4) Executing the development, post bake, etc.

Specifically, a mask for peripheral exposure with a unit shot region 9generally opening is previously prepared in addition to the mask(reticle), for example. The wafer peripheral exposure and the regularexposure are executed as a series of processing in such a way that themask is replaced with the prepared one during the regular exposure. Now,it is noted that as shown in FIG. 13, what is targeted for the regularexposure is an actual unit shot region 9 r, and what is targeted for thewafer peripheral exposure processing is a dummy unit shot region 9 d.The wafer-peripheral region 6 described with reference to FIG. 12 isusually included in a set including all the dummy unit shot regions 9 d.

The primary aligner inside exposing method in which the masks are usedhas the advantage that almost all of the peripheral portions of thewafer 1 make regions similar to the bulk device region while thethroughput of the regular exposure is somewhat reduced (e.g. dust isreduced).

In the embodiment described here, the mask for peripheral exposure isformed on a mask substrate different from that of the mask for regularexposure. However, the masks may be formed in different parts of thesame substrate. In the case of forming the masks in the same substrate,the time required for the replacement of the mask is shortened. In thecase of the masks formed in different substrates, the shot area of theregular exposure can be made larger sufficiently.

5. Description of an Important Part of the Wafer Process in the Methodfor Manufacturing a Semiconductor Integrated Circuit Device According toAnother Embodiment Hereof (in STI Preceding Process) (with Reference toFIGS. 14 to 22, Mainly)

In this section, a modification of the wafer process described in thesection 1 will be described. The description below covers themodification, parts of which make the detailed description of the waferprocess presented in the section 1, and the description concerning amodification of the reverse oxide film etching.

FIG. 14 is a sectional view of the wafer-inward region for explaining animportant part (the step of SOI wafer introduction) of a wafer processin a method for manufacturing a semiconductor integrated circuit device(STI preceding process) according to another embodiment hereof. FIG. 15is a sectional view of the wafer-inward region for explaining animportant part (the step of forming a resist pattern for trenchformation) of the wafer process in the method for manufacturing asemiconductor integrated circuit device (STI preceding process)according to the embodiment. FIG. 16 is a sectional view of thewafer-inward region for explaining an important part (the step of trenchformation) of the wafer process in the method for manufacturing asemiconductor integrated circuit device (STI preceding process)according to the embodiment. FIG. 17 is a sectional view of thewafer-inward region for explaining an important part (the step ofburying an STI insulative film) of the wafer process in the method formanufacturing a semiconductor integrated circuit device (STI precedingprocess) according to the embodiment. FIG. 18 is a sectional view of thewafer-inward region for explaining an important part (the step offorming a resist pattern for reverse oxide film etching) of the waferprocess in the method for manufacturing a semiconductor integratedcircuit device (STI preceding process) according to the embodiment. FIG.19 is a sectional view of the wafer-inward region for explaining animportant part of the wafer process (the step of reverse oxide filmetching) in the method for manufacturing a semiconductor integratedcircuit device (STI preceding process) according to the embodiment. FIG.20 is a sectional view of the wafer-inward region for explaining animportant part (step of CMP and removal of silicon nitride film, etc.)of the wafer process in the method for manufacturing a semiconductorintegrated circuit device (STI preceding process) according to theembodiment. FIG. 21 is a sectional view of the wafer-inward region forexplaining an important part (the step of processing a resist film forremoval of BOX & SOI layers) of the wafer process in the method formanufacturing a semiconductor integrated circuit device (STI precedingprocess) according to the embodiment. FIG. 22 is a sectional view of thewafer-inward region for explaining an important part (BOX & SOIlayers-removing step) of the wafer process in the method formanufacturing a semiconductor integrated circuit device (STI precedingprocess) according to the embodiment. The important parts of the waferprocess in the method for manufacturing a semiconductor integratedcircuit device (STI preceding process) according to the embodiment willbe described with reference to the drawings.

First, a P-type SOI semiconductor wafer 1 similar to the wafer shown inFIG. 1 is prepared as shown in FIG. 14.

Then, a pad silicon oxide film 21 having a thickness of e.g. about 10 nmis formed almost all over the surface of the wafer 1 on the side of thefront face 1 a by e.g. CVD (Chemical Vapor Deposition), as shown in FIG.15. Subsequently, a silicon nitride film 22 for a stopper of CMP(Chemical Mechanical Polishing) is formed by e.g. CVD almost all overthe surface of the wafer 1 on the side of the front face 1 a to have athickness of e.g. about 60 nm. Then, a resist film 18 for trenchformation is formed almost all over the surface of the wafer 1 on theside of the front face 1 a; the resist film 18 for trench formation ispatterned by e.g. a typical photolithography.

Subsequently, as shown in FIG. 16, a trench which will form an STIregion is formed by e.g. anisotropic dry etching while using, as a mask,the patterned resist film 18 for trench formation. In this embodiment,the trench extends through the BOX layer 14 and reaches the inside ofthe substrate 1 s. By making the arrangement like this, theharmonization with the depth of the trench in the bulk device region 4can be ensured.

Also, the mutual isolation between back-gate regions in the SOI deviceregion 3 can be enhanced.

Subsequently, a liner silicon oxide film is formed on a semiconductorsurface exposed on the side of the front face 1 a of the wafer 1 bythermal oxidation, for example (which is not shown to avoid increasingthe complexity of the drawing).

Then, as shown in FIG. 17, a silicon oxide film is formed as an STIinsulative film 17 almost all over the surface of the wafer 1 on theside of the front face 1 a by e.g. HDP (High Density Plasma)-CVD (thesilicon oxide film may be formed according to another method).

Subsequently, as shown in FIG. 18, a resist film 19 for reverse oxidefilm etching is formed almost all over the surface of the wafer 1 on theside of the front face 1 a, and patterned by e.g. the typicalphotolithography, thereby forming a resist film 19 for reverse oxidefilm etching. In this case, in order to relatively increase the amountof polishing the STI insulative film 17 of the bulk device region 4, thereverse-opening-size-reduction rate in the bulk device region 4 is madea relatively small value according to thebulk-device-side-etching-amount-increasing method, which includes tomake the rate a negative value, namely to make the opening wider thanthe corresponding active region). Substantially, the STI insulative film17 is etched back by e.g. anisotropic dry etching while using as a mask,the patterned resist film 19 for reverse oxide film etching. After that,the disused resist film 19 for reverse oxide film etching is removed bye.g. ashing.

Next, CMP is executed on the side of the front face 1 a of the wafer 1,whereby the front face of the wafer is planarized. Then, silicon nitridefilm 22 is removed by e.g. wet etching, in which the etchant usedtherefor is e.g. a hot phosphoric acid. Subsequently, the pad siliconoxide film 21 is removed by e.g. wet etching, in which the etchant ise.g. a hydrofluoric acid-based etchant. As a result, the structure asshown in FIG. 20 is obtained. It is clear from FIG. 20 that the heightof the top of the STI region 17 b (second STI region) of the bulk deviceregion is lower than the top of the STI region 17 s (first STI region)of the SOI device region. In addition, the SOI layer 15 b of the bulkdevice region is smaller in thickness than the SOI layer 15 s of the SOIdevice region. This is because the amount of etching back of the STIinsulative film 17 in the bulk device region 4 is larger in the reverseoxide film etching.

Next, as shown in FIG. 21, a resist film 16 for bulk device regiondefinition is formed almost all over the surface of the wafer 1 on theside of the face 1 a thereof. The resist film 16 for bulk device regiondefinition is patterned by e.g. a typical photolithography.Subsequently, the patterned resist film 16 for bulk device regiondefinition is used as a mask to remove the SOI layer 15 in the bulkdevice region 4 and in the wafer-peripheral region 6 by e.g. dryetching, in which e.g. a halogen-based etching gas is used. Then, theBOX layer 14 is removed in the bulk device region 4 and in thewafer-peripheral region 6 by e.g. wet etching, in which e.g. ahydrofluoric acid-based etchant is used. After that, the disused resistfilm 16 for bulk device region definition is removed by e.g. ashing, andthen the structure as shown in FIG. 22 is obtained.

The STI insulative film 17 is buried in each trench as shown in FIG. 22the STI regions 17, 17 s and 7 b, i.e. the first and second STI regions17 s and 17 b are formed. In this case, as clear from FIG. 22, an STIheight Htb (i.e. bulk device region STI height) in the bulk deviceregion 4 is relatively low with respect to the front face of thesemiconductor substrate 1 s. This is useful to avoid that a stepdeteriorates the effect of the photolithography.

The exposure of the resist film 16 for bulk device region definition inthe wafer-peripheral region 6 has been described in detail in thesections 3 and 4, and therefore the description thereof is omitted here.

The subsequent steps are the same as those described in the section 1and therefore, the description thereof is not repeated.

The STI preceding process is arranged based on the method such that anSTI region is formed ahead, which has a track record in conventional useand therefore, the STI preceding process has the advantage that the highprocess reliability is achieved.

6. Supplementary Explanation Concerning the Embodiments (Including theModifications), and General Consideration (with Reference to FIGS. 23 to26, Mainly)

FIG. 23 is a wafer top view showing an example of a harmful effect on aboundary portion of the bulk device region and the STI region, and thelike in the case where the height Dtb of the bulk device region STI ishigh (at the time of the completion of a gate electrode-processingstep). FIG. 24 is a sectional view showing a wafer-inward region in STIforming process in a simple STI preceding process which is a comparativeexample (trench-burying step), FIG. 25 is a sectional view showing thewafer-inward region in the STI forming process in the simple STIpreceding process which is a comparative example (BOX & SOIlayers-removing step). FIG. 26 is a wafer sectional view for explainingthe outline of the method for manufacturing a semiconductor integratedcircuit device according to one embodiment hereof (BOX & SOIlayers-removing preceding process). The supplementary explanationconcerning the embodiments (including modifications), and the generalconsideration thereof will be made with reference to the drawings.

(1) General Consideration on the Microfabrication of CMOS IntegratedCircuits

With the progress of microfabrication of CMOS integrated circuits, thespeedup of LSI (Large Scale Integration) and increase in integrationthereof have been advanced. In parallel with this, it has been aprerequisite to reduce the power consumption to prevent the powerconsumption by a chip from exceeding the capacity of cooling it. Forthis purpose, it is necessary to lower a source voltage, and thetransfer from conventional bulk structure transistors to transistors oftotal depletion type SOI structure which is advantageous for a low poweroperation, and transistors of a multi-gate structure (so-called FINstructure) has been considered.

One of possible device structures for such transistors is specificallythe BOX type SOI substrate. Along such line, the development of a logiccircuit with an ultra-low voltage operation (the operation voltage ise.g. 0.4 volts or less, approximately) has been progressed.

In the case of incorporating both of an SOI type transistor in a logiccircuit part, and a bulk type transistor in a peripheral circuit part inan actual integrated circuit device, it is necessary to form the SOIdevice region and the bulk device region separately in its manufacturingprocess. Specifically, a process such that an SOI type semiconductorwafer is used, and an STI device isolation structure is formed both inthe SOI device region and the bulk device region is required. Theabove-described embodiments (including the modifications) are arrangedto solve the various problems in forming an STI device isolationstructure.

(2) Comparative Example and Concrete Description of the Problems Thereof(with Reference to FIGS. 23 to 25, Mainly)

The comparative example is in connection with a conventionally oftenused “STI preceding and uniform reduction reverse oxide film etchingmethod”. With the exception that the uniform reduction method is appliedin reverse oxide film etching, the method is the same as the processdescribed in the section 5, and the reverse oxide film etching includedin the method is the same as the process described in the section 1.Therefore, only parts of the comparative examples corresponding to partsof the process described with reference to FIGS. 21 and 22 in thesection 5 will be described below.

In the case of applying the uniform reduction method to steps associatedwith FIGS. 18 and 19, the structure as shown in FIG. 24 is obtained,which corresponds to FIG. 20. Specifically, as shown in FIG. 24, the top(upper face) of the STI region 17 b (second STI region) of the bulkdevice region, and the top (upper face) of the STI region 17 s (firstSTI region) of the SOI device region coincide with each other in height.Also, their lower faces are located at the same height.

Next, as shown in FIG. 25, a resist film 16 for bulk device regiondefinition is formed almost all over the surface of the wafer 1 on theside of the front face 1 a in the same way as described with referenceto FIG. 21, and The resist film 16 for bulk device region definition ispatterned by e.g. a typical photolithography. Subsequently, thepatterned resist film 16 for bulk device region definition is used as amask to remove the SOT layer 15 in the bulk device region 4 and in thewafer-peripheral region 6 by e.g. dry etching, in which e.g. ahalogen-based etching gas is used. Then, the BOX layer 14 is removed inthe bulk device region 4 and in the wafer-peripheral region 6 by e.g.wet etching, in which e.g. a hydrofluoric acid-based etchant is used. Asclear from FIG. 25, the height Htb of the bulk device region STI in thecomparative example is relatively higher than that in the case of thesections 1 and 5. If in this condition, e.g. the patterning of a gateelectrode as described with reference to FIG. 6 is executed, anabnormality is produced in the width of the gate electrode 25 in aboundary portion (i.e. the STI stepped portion 26) between the activeregion BA of the bulk device region 4 with significantly large steps andthe STI region 17 surrounding it as shown in FIG. 23.

(3) Description of the Outline of the Method for Manufacturing aSemiconductor Integrated Circuit Device According to One EmbodimentHereof (BOX & SOI Layers-Removing Preceding Process) (with Reference toFIG. 26, Mainly)

In contrast, in the method for manufacturing a semiconductor integratedcircuit device (BOX & SOI layers-removing preceding process) accordingto the embodiment, the BOX layer 14 and the SOI layer 15 are removedbefore forming the STI region 17 s in the SOI device region 3 to extendthrough the BOX layer 14, as shown in FIG. 26. By making the arrangementlike this, a surface step around the STI region 17 b e.g. in the bulkdevice region 4 can be made smaller, as shown in FIG. 5.

In addition, the method for manufacturing a semiconductor integratedcircuit device (BOX & SOI layers-removing preceding process) accordingto the embodiment is not limited to the formation of the STI region 17 swhich extends through the BOX layer 14, and it is effective to the caseof forming the STI region 17 s which does not extend through the BOXlayer 14 likewise. In this case, there is an advantage as follows. Ifthe method is arranged not to have the step for forming an epitaxialsemiconductor layer at least on the bulk device region after the BOX &SOI layers-removing step and before the STI region forming step inaddition to the above-described conditions, the process can besimplified. In other words, the method is advantageous in that there isno need to have a complicated epitaxial process and the like to raisethe height of the substrate upper face in the bulk side.

7. Summary

The invention made by the inventor has been concretely described abovebased on the embodiments. However, the invention is not limited to theembodiments. It is obvious that various changes and modifications may bemade without departing from the subject matter thereof.

While the embodiments have been described specifically while chieflytaking the gate-first method as an example, the invention is not limitedto the embodiments. It is obvious that the invention is applicable toFUSI process, High-k first & gate last method, High-k & gate lastmethod, P-side gate last hybrid method, etc.

What is claimed is:
 1. A manufacturing method for semiconductorintegrated circuit device comprising: (a) removing an SOI layer and aBOX layer in a part to make a bulk device region in each chip region ona first principal face side of an SOI type semiconductor wafer; (b)after the step (a), forming a first STI region to extend through the BOXlayer in a part to make an SOI device region in each chip region on thefirst principal face side of the SOI type semiconductor wafer, andforming a second STI region in the bulk device region in each chipregion on the first principal face side of the SOI type semiconductorwafer; and (c) after the step (b), forming MISFETs in the SOI deviceregion and the bulk device region respectively.
 2. The method formanufacturing a semiconductor integrated circuit device according toclaim 1, wherein a lower end portion of the second STI region is lowerthan that of the first STI region.
 3. The method for manufacturing asemiconductor integrated circuit device according to claim 2, whereinthe step (c) includes: (c1) patterning a gate electrode of the MISFET.4. The method for manufacturing a semiconductor integrated circuitdevice according to claim 3, wherein the step of forming an epitaxialsemiconductor layer at least on the bulk device region is not includedafter the step (a) and before the step (b).
 5. The method formanufacturing a semiconductor integrated circuit device according toclaim 4, wherein the step (b) further includes: forming an alignmentmark to use in the step (c) in a dicing region on the first principalface side of the SOI type semiconductor wafer, the region having the SOIand BOX layers removed therefrom.
 6. The method for manufacturing asemiconductor integrated circuit device according to claim 5, whereinthe alignment mark is mainly composed of an STI insulative film formedconcurrently with formation of the first and second STI regions.
 7. Themethod for manufacturing a semiconductor integrated circuit deviceaccording to claim 4, wherein the step (a) further includes: removingthe SOI and BOX layers in a wafer-peripheral region on the firstprincipal face side of the SOI type semiconductor wafer.
 8. The methodfor manufacturing a semiconductor integrated circuit device according toclaim 7, wherein a part to remove the SOT and BOX layers from thewafer-peripheral region is defined by peripheral exposure.
 9. The methodfor manufacturing a semiconductor integrated circuit device according toclaim 7, wherein a part to remove the SOI and BOX layers from thewafer-peripheral region is defined by exposure using a mask pattern. 10.The method for manufacturing a semiconductor integrated circuit deviceaccording to claim 8, wherein the peripheral exposure is executed beforea primary exposure for defining the bulk device region in each chipregion.
 11. A method for manufacturing a semiconductor integratedcircuit device comprising: (a) removing an SOI layer and a BOX layer ina part to make a bulk device region in each chip region on a firstprincipal face side of an SOI type semiconductor wafer; (b) after thestep (a), forming a first STI region in a part to make an SOI deviceregion in each chip region on the first principal face side of the ofthe SOI type semiconductor wafer, and forming a second STI region in thebulk device region in each chip region on the first principal face sideof the SOI type semiconductor wafer; and (c) after the step (b), formingMISFETs in the SOI device region and the bulk device regionrespectively, wherein the step of forming an epitaxial semiconductorlayer at least on the bulk device region is not included after the step(a) and before the step (b).
 12. The method for manufacturing asemiconductor integrated circuit device according to claim 11, wherein alower end portion of the second STI region is lower than that of thefirst STI region.
 13. The method for manufacturing a semiconductorintegrated circuit device according to claim 12, wherein the step (c)includes: (c1) patterning a gate electrode of the MISFET.
 14. The methodfor manufacturing a semiconductor integrated circuit device according toclaim 13, wherein the step (b) further includes: forming an alignmentmark to use in the step (c) in a dicing region on the first principalface side of the SOI type semiconductor wafer, the region having the SOIand BOX layers removed therefrom.
 15. The method for manufacturing asemiconductor integrated circuit device according to claim 14, whereinthe alignment mark is mainly composed of an STI insulative film formedconcurrently with formation of the first and second STI regions.
 16. Themethod for manufacturing a semiconductor integrated circuit deviceaccording to claim 13, wherein the step (a) further includes: removingthe SOI and BOX layers in a wafer-peripheral region on the firstprincipal face side of the SOI type semiconductor wafer.
 17. The methodfor manufacturing a semiconductor integrated circuit device according toclaim 16, wherein a part to remove the SOI and BOX layers from thewafer-peripheral region is defined by peripheral exposure.
 18. Themethod for manufacturing a semiconductor integrated circuit deviceaccording to claim 16, wherein a part to remove the SOI and BOX layersfrom the wafer-peripheral region is defined by exposure using a maskpattern.
 19. The method for manufacturing a semiconductor integratedcircuit device according to claim 17, wherein the peripheral exposure isexecuted before a primary exposure for defining the bulk device regionin each chip region.